Elastic Peak Fitting for LESCO 0.26 LV

Beamtime session: HC-6093

RIXS file name: Online_analysis_EuLSCO_26_1_B_big_CDW_25K_andor1.spec

XAS file name: EuLSCO_26_1_B_big_CDW_25K.h5. #49 is the trigger scan, #50 is the ascan

Processed RIXS data: lesco_p26_cu_edge_normalized.json

Sample: Eu_LSCO p=0.26

Polarization: LV

Temperature: 25 K

Counting time of each spectrum: 1200 seconds

Resolution: 0.052 eV

Data Processing

This analysis uses three different normalization approaches applied to the same raw dataset:

1. Unnormalized data (intensity_unnormalized): Raw spectral intensities without any normalization
2. dd-normalized data (intensity_dd_norm): Data normalized by the integrated intensity in the dd excitation range (0.8–3.5 eV)
3. Self-absorption corrected data (intensity_self_absorp_norm): Data corrected for self-absorption effects using XAS data

All three datasets were generated from the self-absorption correction analysis and saved in the normalized JSON file.

The fitting model consists of three Gaussian peaks plus a linear background:

$$I(E) = I_{\text{elastic}}(E) + I_{\text{phonon}}(E) + I_{\text{magnon}}(E) + I_{\text{background}}(E)$$

Individual Components

1. Elastic Peak: $I_{\text{elastic}}(E) = A_1 \exp\left(-\frac{(E - x_1)^2}{2\sigma_1^2}\right)$
2. Phonon Peak: $I_{\text{phonon}}(E) = A_2 \exp\left(-\frac{(E - x_2)^2}{2\sigma_2^2}\right)$
3. Magnon Peak: $I_{\text{magnon}}(E) = A_3 \exp\left(-\frac{(E - x_3)^2}{2\sigma_3^2}\right)$
4. Linear Background: $I_{\text{background}}(E) = \max(0, \text{slope} \cdot E)$

where $\sigma_i = \frac{\text{FWHM}_i}{2\sqrt{2\ln(2)}}$

Parameter Constraints

• Energy range: -0.15 to 0.5 eV
• Elastic center: -0.1 to 0.1 eV
• Phonon center: 0 to 0.2 eV
• Magnon center: 0.06 to 0.6 eV
• Resolutions: Constrained around experimental value (0.05 ± 0.01 eV)

The following figures show the fitting results for each normalization method. Each subplot displays:

• Blue dots: Experimental data
• Yellow line: Overall fit
• Gray area: Elastic peak component
• Orange area: Phonon peak component
• Teal area: Magnon peak component
• Dashed red line: Linear background

The elastic peak amplitude (A₁) is displayed in each panel for comparison.

Normalized Elastic Intensity vs H

Comparison Plots

The first plot shows all three normalized datasets overlaid for direct comparison of trends, while the second plot shows them in separate panels to better visualize individual behaviors. Each dataset is normalized to its own maximum value.

Gaussian Fits: Gray dashed lines show Gaussian fits to each normalized dataset, providing a smooth representation of the momentum dependence and enabling quantitative comparison of the peak positions and widths across normalization methods.

Summary Statistics

Unnormalized: - Mean amplitude: 1.235 ± 0.142 - Range: 1.005 to 1.536

dd-normalized: - Mean amplitude: 1.052 ± 0.113 - Range: 0.870 to 1.219

Self-absorption corrected: - Mean amplitude: 3.477 ± 0.661 - Range: 2.487 to 4.806